基于控制单元的农村生活污水处理优化模型

基于系统动力学(SD)模拟模型和Powell优化模型,建立了农村生活污水污染物削减量与治理费用的SD-Powell模拟优化耦合模型,该模型可模拟预测污染物排放量,建立污染物削减量与治理费用函数关系.在此基础上,以污水治理费用最小为目标,以污水处理量为约束条件,对区域污染物削减量进行空间优化,得到最小治理费用下的最大污染物削减量.以常州市为例进行实证分析,模拟结果显示,2020年常州市农村生活污水COD和NH3-N排放量将达到16583t和2551t,分别比2008年增长4.60%和4.59%.采用聚类方法将常州市51个乡镇划分为4类控制单元,得到4类地区COD、NH3-N治理费用函数.各单位治理资金削减量存在明显差异,COD削减率的排序依次为:I类控制单元413kg/万元、IV类控制单元 380kg/万元、II类控制单元352kg/万元、III类控制单元348kg/万元,NH3-N削减率的排序依次为:III类控制单元65kg/万元、I类控制单元64kg/万元、IV类控制单元58kg/万元、II类控制单元54kg/万元,全区域削减率达到100%需要的治理费用约为16870万元.污染物削减空间优化结果显示,基于控制单元空间优化的削减效率高于平均分配的结果,治理费用在1000 -16870万元/a范围,COD、NH3-N的削减率分别提高6.4%和7.4%,4类地区的优先排序顺序依次为I类,IV类,II类和III类.

Optimization of rural domestic sewage treatment models

Rural sewage treatment is an important task of the New Rural Construction in China, which also plays a key role in improving the rural ecological environment. In this study, using system dynamic (SD) model and Powell optimization model, a SD-Powell coupled model with simulation and optimization function was set up to simulate and predict the amount of pollutant discharge, and to establish the functional relationship of pollutant reduction and cost. Taking Changzhou City in Jiangsu Province as a case study, the calculated results indicate that COD and ammonia emissions will reach up to 16583 t and 2551 t in 2020 respectively, increased by 4.60% and 4.59% compared to 2008. The 51 towns in Changzhou City were divided into four categories of control units using clustering method. The treatment cost functions for COD and ammonia in different control units were obtained, with the treatment cost in four units varying from 348 kg to 413 kg per ten thousand Yuan RMB for COD, and 54 kg to 65 kg per ten thousand Yuan RMB for ammonia. The total cost will be 168.7 million RMB Yuan if the pollutant reduction rate in the whole area reaches 100%. The results show that the pollutant reduction rate by cost optimization was better than the cost average allocation. Compared to average allocation results, the method used in this study could increase reduction effectiveness of the two pollutants COD and ammonia by 6.4% and 7.4%, respectively. The optimal treatment cost was between 10and 168.7 million RMB per year under different reduction rates and the treatment cost for priority unit was in the order of I>IV>II >III.